Automatic coffee maker with liquid level sensor and siphon control

ABSTRACT

Cold water is supplied to a basin until it reaches a liquid level sensor and then is siphoned from the basin into a hot water tank from which hot water is siphoned for coffee brewing purposes. Various cold water siphon arrangements are provided together with various means for varying the volume of cold water supplied to the basin.

[ 51 Feb. 26, 1974 United States Patent [191 Martin 3 354,8l0 11/1967Lorang 3,366,034 l/l968 Karlen 3,494,276 2/1970 Martin 3,513,767 5/1970Bloomfield... 3,691,933 9/1972 Martin Primary Examiner-Robert W. JenkinsSpringfield, Ill.

Dec. 15, 1972 Appl. No.: 315,409

Attorney, Agent, or Firm-Robert R. Lockwood [22] Filed:

[57] ABSTRACT Cold water is supplied to a basin until it reaches'a liq-8 352? uid level sensor and then is siphoned from the basin [58] Fieid283 295 into a hot water tank from which hot water is siphoned forcoffee brewing purposes. Various cold water siphon arrangements areprovided together with various means for varying the volume of coldwater supplied to the basin.

[56] References Cited UNITED STATES PATENTS 99/282 19 Claims, 14 DrawingFigures 3,220,334 ll/l965 Martin............

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PATENTEUFEBZGIQM sum 1 OF 4 mmkqk 38 PATENTEU FEB 2 61974 SHEET 4 BF 4AUTOMATIC COFFEE MAKER WITH LIQUID LEVEL SENSOR AND SIPHON CONTROL Thisinvention relates to coffee brewing apparatus and constitutes animprovement over the coffee brewer disclosed in Martin U.S. Pat. No.3,691,933, issued Sept. 19, 1972.

The coffee brewer disclosed in the above patent employs a dump valve inthe cold water inlet pipe to the hot water tank from'the cold waterbasin. The dump valve is closed by a winding that is energized at thetime that a valve is opened to permit thefflow of cold water to thebasin and is opened by a spring when the water level in the basinreaches a liquid level sensor at which time the flow of cold water tothe basin is shut off. While this arrangement is satisfactory, thepresence of the dump valve and control therefor cause an undesirablecomplication and expense in first cost and maintenance.

' Accordingly, an important object of this invention is to provide acoffee brewer that does not require a dump valve while retaining theadvantages of the system in which it is employed. Other objects are: Toprovide for siphoning the cold water out of the cold water basin-intothehot water tank from which hot water is siphoned for coffee brewingpurposes; to start the siphon action from the cold water basin .when thewater therein reaches a predetermined level sufficient to brew aquantity of coffee extract; to prevent the initiation of the siphonaction from the cold water basin as long as cold water continues to flowinto it; to vent to the atmosphere the upper end of the cold water inletpipe; to adjust the vertical position of a liquid level sensor in thecold water basin to vary the volume of cold water supplied thereto and:thereby the volume of hot water available for coffee brewing purposes;to extend the cold water inlet pipe for the hot water tank into the coldwater basin by an inverted U-shaped upper end portion opening near thebottom of the basin; to provide a sump in the bottom of the basin intowhich the inverted U-shaped upper end portion opens; to employ aT-shaped connection or a Y-shaped connection between the inlet waterline and the inverted U-shaped upper end portion of the cold water inletpipe; to vent the upper end of the cold water inlet at the upper end ofthe hot water tank to the atmosphere to prevent .siphoning of the hotwater into the cold water basin; to employ a liquid level sensor of thelight responsive type for controlling the volume of cold water flowingto the cold water basin; and to provide for adjusting the volume of coldwater that is supplied to the cold water basin for each coffee brewingsequence.

In the drawings:

FIG. 1 is a view, partly in side elevation, partly in section and partlydiagrammatic of an automatic coffee brewer in which the presentinvention is embodied.

FIG. 2 shows diagrammatically the circuit connec- FIG. 4 shows how theprism of the liquid level sensor functions for bending light rays whencontacted by water.

FIG. 5 shows a modified form of the coffee brewer having the vent pipeextending upwardly from the upper end of the cold water inlet pipe.

FIG. 6 shows a modified form of the invention employing a T-connectionbetween the cold water inlet pipe and the discharge end of the inletwater line.

FIG. 7 shows a further modification of the arrangement illustrated inFIG. 6.

FIG. 8 shows a still further modification of the arrangement as shown inFIG. 6.

FIG. 9 shows how volume varying means can be employed in the cold waterbasin.

FIG. 10 shows an alternate position of the cold water varying means.

FIG. 11 shows a further embodiment of the cold water varying means.

FIG. 12 illustrates how the liquid level sensor can be varied inelevation to change the volume of cold water in the cold water basin.

FIG. 13 is a top plan view of the spacer employed in FIG. 12.

FIG. 14 is a view, in end elevation, of the spacer shown in FIG. 13.

In FIG. 1 reference character 10 designates, generally, an automaticcoffee brewer embodying this invention. The coffee brewer 10 includes ahot water tank 1 1 containing water 12 that normally is filled to thelevel indicated at 13. The water 12 is maintained at the desiredtemperature by an immersion electric heating element 14 the energizationof which is controlled by a thermostat 15. Contacts 16 for thethermostat 15 are illustrated in FIG. 2 to which further reference willbe made.

In order to maintain atmospheric pressure at the upper end of the hotwater tank 11 a vent tube 17 is employed. Hot water from the tank 11 issiphoned out through a siphon tube 18 to a spray head 19 that overliesground coffee 20 on a paper filter 21 which is located in a funnel 22.Coffee extract 23 flows from the funnel 22 into a beaker 24 therebelow.The beaker 24 is mounted on a warmer 25 to maintain the coffee extractat the desired temperature.

Positioned above the hot water tank 11 is a cold water basin 26 that isprovided with a removable cover 27. A given quantity 28 of cold waterflows into the cold water basin 26 in a manner to be described and flowsout of it into the hot water tank 11. Cold water from a suitable sourceunder pressure flows through an inlet water line 29 to the cold waterbasin 26 under the control of a valve 30. A solenoid 31 is arranged toopen the valve 30 which is arranged to automatically close when thesolenoid 31 is deenergized.

The discharge end 32 of the inlet water line 29 curves downwardly andopens into a sump 33 in the bottom of the cold water basin 26.

Above the lower end of the downwardly curved end 32 of the inlet waterline 29 is a Y-connection 34 to one leg 35 of an inverted U-shaped upperend 36 of a cold water inlet pipe that is shown, generally, at 37. Thisarrangement provides for siphoning cold water from the sump 33 into thehot water tank 11. The other leg 38 of the U-shaped upper end 36 extendsthrough a fitting 39 that projects downwardly through the bottom of thecold water basin 26 and into a threaded boss 40 that extends upwardlyfrom a cover 41 for the hot water tank 11. Cold water from the coldwater basin 26 is siphoned by the upper end 36 of the cold water inletpipe 37 into the upper end 42 of the lower end 43 of the cold waterinlet pipe 37 which extends upwardly from the lower portion of the hotwater tank 11 to the cover 41. The upper end 42 is telescoped over anapertured boss 44 that depends from the cover 41 and is in alignmentwith the threaded boss 40. A screw 45 serves to hold the lower end 43 inposition on the boss 44.

It will be observed that a slot 46 is formed in the apertured boss 44 toplace the upper end of the large diameter lower end 43 of the cold waterinlet pipe 37 in communication with the atmosphere through the vent tube17. The reason for the provision of the slot 46 is to prevent siphoningof the hot water 12 in the tank 11 into the cold water basin 26 while itis being filled from the inlet water line 29.

It is desirable to fill the cold water basin 26 to the level 51 which isabove the bight 52 of the inverted U- shaped upper end 36. For thispurpose there is employed a liquid level sensor that is indicated,generally, at 53. In FIG. 2 the liquid level sensor 53 is represented bynormally closed contacts 54 which are in series with normally opencontacts 55 of a relay'that is indicated, generally, at 56 and employs awinding 57. The system shown in FIG. 2 is energized over conductors 58and 59 that are connected to a suitable 115V. 6OI-lz. source, forexample. A main switch 60, when closed, connects the system forenergization to the source. When the main switch 60 is closed aconductor 61 is connected directly for energization to the conductor 58.There is provided a manually operable start switch 62 having normallyopen contacts 63. The start switch 62 is operated to start the brewingcycle. On closure of contacts 63 an obvious energizing circuit iscompleted for solenoid 31 to open valve 30 andpermit cold water to flowfrom the inlet water line 29 into the cold water basin 26. Winding 57also is energized to close contacts 55 and provide a holding circuit forwinding 57 and solenoid 31 through the normally closed contacts 54 ofthe liquid level sensor 53.

FIG. 3 illustrates the circuit details of the liquid level sensor 53which may be employed to respond to the level 51 of the cold water 28 inthe cold water basin 26 to effect closure of the valve 30 bydeenergizing solenoid 31. This circuit includes an SCR 66 theconductivity of which is controlled by a light responsive device 67 froma light source 68 which may be a neon lamp. Light rays, indicated by abroken line 69, are reflected by a prism 70 and are applied to the lightresponsive device 67. Under these conditions the SCR 66 conducts halfcycles of the alternating current to maintain and energize the winding57 and the solenoid 31. A diode 71 is connected across conductors 64 and65 to reduce chatter of the contacts 55 of the relay 56.

In operation the tank 11 normally is filled with hot water 12 to thelevel indicated at 13. The funnel 22 is charged with ground coffee andplaced in operative position under the spray head 19. After closure ofmain switch 60 the start switch 62 is depressed to energize solenoid 31and winding 57 of the relay 56. The holding circuit through contacts 55is completed, valve 30 is opened and cold water flows into the sump 33until it reaches the level 51 at which time the cold water impinges onthe prism 70. When this occurs, as illustrated in FIG. 4, the lightrays, instead of being reflected unto the light responsive device 67 arerefracted as indicated at 72'. The SCR 66 ceases to conduct and ineffect opens normally closed contacts 54. Solenoid 31 is deenergized.Also winding 57 is deenergized and contacts 55 are opened.

It will be observed that the level 51 in the cold water basin 26 isabove the bight 52 of the inverted U-shaped upper end 36 of the coldwater inlet pipe 37. On cessation of flow of cold water through theinlet water line 29, the inverted U-shaped upper end 36 is filled withwater and starts a siphon action which transfers the cold water 28 tothe lower end of the hot water tank 1 1 through the cold water inletpipe 37. The hot water tank 11 then is completely filled and hot waterstarts to siphon out of it through the siphon tube 18 when the level ofthe hot water in it rises above its highest elevation. There are thentwo siphon actions, the first is from the cold water basin 26 into thehot water tank 11 while the second is from the hot water tank 11 to thespray head 19 for spraying hot water over the ground coffee 20 on thefilter 21 in the funnel 22 to brew the coffee extract 23. In FIG. 1 itwill be observed that a baffle or enclosure 73 surrounds the upperportion of the liquid level sensor 53. An inlet opening 74 permits flowof cold water into the vicinity of the prism 70. However, the prism isprotected against variations in the level of the cold water 28 so that atrue level 51 is represented in the baffle or enclosure 73 so that thequantity of cold water 28 in the cold water basin 26 can be accuratelypredetermined for each successive brewing operation.

In FIG. 1 it will be observed that a suitable gasket 76 is employed formaking a water tight connection to the liquid level sensor 53. Below itthere is provided a spacer 77 that is relatively thick so that the upperend of the prism 70 is located at a maximum distance indicated at 78from the cover 27. It will be understood that the prism 70, when thespacer 77 is employed, is located at its lowest elevation in the coldwater basin 26 with the result that the liquid level 51 is at its lowestelevation. For example, using the relatively thick spacer 77 thequantity of cold water 28 flowing into the cold water basin 26 may be 60ounces.

In FIG. 12 a thinner spacer 79 is employed with the result that theupper end of the prism 70 is located at an intermediate distance 80 fromthe cover 27 and the quantity of cold water flowing into the cold waterbasin 26 may be 62 ounces. FIGS. 13 and 14 show the details of thespacer 79.

In FIG. 9 no spacer is employed with the result that there is a minimumdistance 82 between the upper end of the prism 70 and the under side ofthe cover 27 This may correspond to a quantity of 64 ounces of coldwater that are permitted to flow into the cold water basin 26 before thevalve 30 is closed by deenergization of the solenoid 31.

The coffee brewer 10, illustrated in FIG. 5, is similar to thatillustrated in FIG. 1 and described hereinbefore except for theprovision of a vent pipe 85 extending through the fitting 39 along sideof the other leg 38 of the inverted U-shaped upper end 36 of the coldwater FIG. 7 shows still another arrangement of the interconnectionbetween the inverted U-shaped upper end 36 and the discharge end 32 ofthe inlet water line 29. In this illustration the T-connection isemployed. However, the stem 88 of the T-shape is connected to thedischarge end 32 while the leg 35 is connected to one end of the barportion of the T-shape while the other end projects into the sump 33.

In FIG. 8 the discharge end 32 of the inlet water line 29 stops at thewall of the cold water basin 26. There is no direct interconnectionbetween the inverted U- shaped upper end 36 of the cold water inlet pipe37 and the inlet water line 29. The arrangement illustrated in FIG. 8 issatisfactory where the flow of incoming cold .water from the inlet waterline 29 is sufficiently rapid to reach the desired elevation in the coldwater basis 26 before the siphon action starts through the cold waterinlet pipe37.

As pointed out hereinbefore the level 51 of the cold water 28 in thecold water basin 26 can be varied for successive coffee brewingoperations by varying the elevation of the prism 70 of the liquid levelsensor 53. Another and preferred manner of varying the elevation of theliquid level 51 is to employ the volume varying means illustrated,generally at 93 in FIGS. 9 and 10. The volume varying means 93 comprisesa member 94 which may be cylindrical or square and has a relativelysmall volume varying section 95 on one side and a relatively largevolume varying section 96 on the other side. Threaded apertures 97 and98 are formed on opposite sides for receiving a bolt 99. When the volumevarying means 93 is positioned as illustrated in FIG. 9 with the bolt 99extending through the cover 27'the volume of the cold water 28 requiredto produce the level 51 may be 62 ounces. When the volume varying means93 is turned upside down, as illustrated in FIG. 10, the volume is 60ounces. With the volume varying means 93 omitted the volume of the coldwater 28 may be 64 ounces.

FIG. 11 shows volume of varying means at 102 in the form of a solidcylinder 103 that is internally threaded as indicated at,104. A bolt 105extends through the cover 27 into the cylinder 103 which can be variablypositioned as desired to effect a corresponding variation in the level51 of the cold water 28 and thereby in its volume. A lock nut 106 isemployed to hold the bolt 105 against turning.

I claim:

1. Coffee brewing apparatus comprising a hot water tank, means forheating water in said tank, a siphon tube for withdrawing hot water fromsaid tank to brew coffee extract, means for placing said tank incommunication with the atmosphere, a cold water basin above said tank, acold water inlet pipe extending upwardly through said tank into saidbasin including an inverted U-shaped upper end portion having itsopening near the bottom of said basin, an inlet water line for supplyingcold water to said basin from a source under pressure, a valve in saidinlet water line, means for opening said valve to cause cold water toflow into said basin, and means for closing said valve when said coldwater reaches a predetermined level in said basin above said invertedU-shaped upper end portion whereupon said cold water is siphoned fromsaid basin into said tank until the level of said cold water in saidbasin is lowered to said downwardly facing opening of said inverted U-shaped upper end portion and hot water is siphoned from said tankthrough said siphon tube.

2. Coffee brewing apparatus according to claim 1 wherein said basin hasa sump in the bottom and said opening to said U-shaped upper end portionfaces downwardly in said sump.

3. Coffee brewing apparatus according to claim 1 wherein said inletwater line opens into the leg of said inverted U-shaped end portionabove said opening near the bottom of said basin.

4. Coffee brewing apparatus according to claim 3 wherein T-shaped meansinterconnects said inlet water line and said inverted U-shaped endportion.

5. Coffee brewing apparatus according to claim 3 wherein Y-shaped meansinterconnects said inlet water line and said inverted U-shaped endportion. I

6. Coffee brewing apparatus according to claim 1 wherein the bight ofsaid inverted U-shaped upper end portion is positioned below andadjacent said predetermined level of cold water in said basin.

7. Coffee brewing apparatus according to claim 1 wherein said means forclosing said valve includes a liquid level sensor.

8. Coffee brewing apparatus according to claim 7 wherein said liquidlevel sensor includes normally closed switch means controlled by a lightresponsive device, a light source and a prism for directing rays fromsaid light source to said light responsive device as long as said prismis not contacted by water in said basin.

9. Coffee brewing apparatus according to claim 1 wherein an air ventline opens into said cold water inlet pipe at the upper end of said hotwater tank.

10. Coffee brewing apparatus according to claim 1 wherein means areprovided for varying the volume of cold water in said cold water basinrequired to reach said predetermined level therein for closing saidvalve.

11. Coffee brewing apparatus according to claim 10 wherein said volumevarying means comprises a member having different volume varyingsections on opposite sides, and means for securing said member in fixedposition in said basin at said predetermined level with one side or theother uppermost.

12. Coffee brewing apparatus according to claim 11 wherein a coveroverlies said basin, a said member is detachably mounted in dependingrelation thereon.

13. Coffee brewing apparatus according to claim 10 wherein said volumevarying means comprises a liquid displacing member, and means forvariably vertically positioning the same relative to said predeterminedlevel in said basin.

14. Coffee brewing apparatus according to claim 10 wherein a coveroverlies said basin, and said volume varying means comprises a liquiddisplacing member, and a screw depending from said cover and threadedinto said member.

15. Coffee brewing apparatus according to claim 10 wherein said meansfor closing said valve when said cold water reaches a predeterminedlevel in said basin includes a liquid level sensor, and said means forvarying the volume of cold water required to reach said level includesmeans for adjusting the vertical position of said liquid level sensor.

16.'Coffee brewing apparatus comprising a hot water tank, means forheating water in said tank, a siphon tube for withdrawing hot water fromsaid tank to brew coffee extract, means for placing said tank incommunication with the atmosphere, a cold water basin above 'said tank,a cold water inlet pipe extending upwardly through said tank into saidbasin including an inverted U-shaped upper end portion having itsopening nearv the bottom of said basin, means for supplying cold waterto said basin until it reaches a predetermined level thereinwhereupon'said cold water is siphoned from said basin into said tankuntil the level of said cold 7 water in said basin is lowered to saiddownwardly facwherein said basin has a sump in the bottom and saidopening in said U-shaped upper end portion faces downwardly in saidsump.

18. Coffee brewing apparatus according to claim 16 an air vent lineopens into said cold water inlet pipe at t the upper end of saidhotwater tank.

19. Cofiee brewing apparatus according to claim 16 wherein an air ventis located at the upper end of the I cold water inlet pipe to place theupper end of said hot water tank in communication with the atmosphereand prevent siphoning of the hot water from said tank into saidbasin. a

1. Coffee brewing apparatus comprising a hot water tank, means forheating water in said tank, a siphon tube for withdrawing hot water fromsaid tank to brew coffee extract, means for placing said tank incommunication with the atmosphere, a cold water basin above said tank, acold water inlet pipe extending upwardly through said tank into saidbasin including an inverted U-shaped upper end portion having itsopening near the bottom of said basin, an inlet water line for supplyingcold water to said basin from a source under pressure, a valve in saidinlet water line, means for opening said valve to cause cold water toflow into said basin, and means for closing said valve when said coldwater reaches a predetermined level in said basin above said invertedU-shaped upper end portion whereupon said cold water is siphoned fromsaid basin into said tank until the level of said cold water in saidbasin is lowered to said downwardly facing opening of said invertedU-shaped upper end portion and hot water is siphoned from said tankthrough said siphon tube.
 2. Coffee brewing apparatus according to claim1 wherein said basin has a sump in the bottom and said opening to saidU-shaped upper end portion faces downwardly in said sump.
 3. Coffeebrewing apparatus according to claim 1 wherein said inlet water lineopens into the leg of said inverted U-shaped end portion above saidopening near the bottom of said basin.
 4. Coffee brewing apparatusaccording to claim 3 wherein T-shaped means interconnects said inletwater line and said inverted U-shaped end portion.
 5. Coffee brewingapparatus according to claim 3 wherein Y-shaped means interconnects saidinlet water line and said inverted U-shaped end portion.
 6. Coffeebrewing apparatus according to claim 1 wherein the bight of saidinverted U-shaped upper end portion is positioned below and adjacentsaid predetermined level of cold water in said basin.
 7. Coffee brewingapparatus according to claim 1 wherein said means for closing said valveincludes a liquid level sensor.
 8. Coffee brewing apparatus according toclaim 7 wherein said liquid level sensor includes normally closed switchmeans controlled by a light responsive device, a light source and aprism for directing rays from said light source to said light responsivedevice as long as said prism is not contacted by water in said basin. 9.Coffee brewing apparatus according to claim 1 wherein an air vent lineopens into said cold water inlet pipe at the upper end of said hot watertank.
 10. Coffee brewing apparatus according to claim 1 wherein meansare provided for varying the volume of cold water in said cold waterbasin required to reach said predetermined level therein for closingsaid valve.
 11. Coffee brewing apparatus according to claim 10 whereinsaid volume varying means comprises a member having different volumevarying sections on opposite sides, and means for securing said memberin fixed position in said basin at said predetermined level with oneside or the other uppermost.
 12. Coffee brewing apparatus according toclaim 11 wherein a cover overlies saId basin, a said member isdetachably mounted in depending relation thereon.
 13. Coffee brewingapparatus according to claim 10 wherein said volume varying meanscomprises a liquid displacing member, and means for variably verticallypositioning the same relative to said predetermined level in said basin.14. Coffee brewing apparatus according to claim 10 wherein a coveroverlies said basin, and said volume varying means comprises a liquiddisplacing member, and a screw depending from said cover and threadedinto said member.
 15. Coffee brewing apparatus according to claim 10wherein said means for closing said valve when said cold water reaches apredetermined level in said basin includes a liquid level sensor, andsaid means for varying the volume of cold water required to reach saidlevel includes means for adjusting the vertical position of said liquidlevel sensor.
 16. Coffee brewing apparatus comprising a hot water tank,means for heating water in said tank, a siphon tube for withdrawing hotwater from said tank to brew coffee extract, means for placing said tankin communication with the atmosphere, a cold water basin above saidtank, a cold water inlet pipe extending upwardly through said tank intosaid basin including an inverted U-shaped upper end portion having itsopening near the bottom of said basin, means for supplying cold water tosaid basin until it reaches a predetermined level therein whereupon saidcold water is siphoned from said basin into said tank until the level ofsaid cold water in said basin is lowered to said downwardly facingopening in said U-shaped upper end portion and hot water is siphonedfrom said tank through said siphon tube.
 17. Coffee brewing apparatusaccording to claim 16 wherein said basin has a sump in the bottom andsaid opening in said U-shaped upper end portion faces downwardly in saidsump.
 18. Coffee brewing apparatus according to claim 16 an air ventline opens into said cold water inlet pipe at the upper end of said hotwater tank.
 19. Coffee brewing apparatus according to claim 16 whereinan air vent is located at the upper end of the cold water inlet pipe toplace the upper end of said hot water tank in communication with theatmosphere and prevent siphoning of the hot water from said tank intosaid basin.